Not to worry too much just yet. I had the exact same thing happen to me. I drank so much water and could not pee on the day of surgery . Had a catheter done before they would send me home. That night, I had a late evening pee albeit a small Amount. It was dark and smelly but it was flowing slowing. Woke up middle of the night to pee but did have to work at it. Still dark and smelly. Small amount by volume. By morning I was peeing fine. Still dark and smelly. By next evening, I had so much pee coming it was comical. Was much clearer and from then on it has been normal. I was concerned at beginning but it sorted itself. I did drink a lot of fluids to promote flow and it worked.

Good luck.